This is a spoiler-free review.
Ok, so this is one of my runner-ups for the best anime this season. The premise is pretty simple: everyone was turned into stone statues and our heroes wake up after ages and try to bring back the lost civilization.
The whole show is based on science and scientific discoveries that we take for granted and that have transformed our lives from savage banana-seeking monkeys that we biologically are. Which is an awesome, new theme in anime that has not been explored. What more do You need?
First - the story.
The plot is structured in a few self-contained arcs that are continuations of each other.
The series is set in a world that has, for all intents and purposes, gone back to the caveman era. The whole point of the story is to get it back to where we are today.
Relationships between each of the characters (especially our two protagonists - in the first story arc) are given adequate time to develop and feel natural. The story sets up their motivations pretty well.
The main theme of the story is to teach the audience about basic science facts (which is awesome) and to show how our lives are different from what they were supposed to be from a biological standpoint. Just for the novelty of the idea, the show is very much worth a watch.
Second: the animation.
The animation is ... ok ... but nothing truly spectacular.
Characters are drawn and animated in a somewhat distinctive way (I felt it's how the western audience would IMAGINE anime) but they look pretty good after You get used to it.
Having said that this is a story-driven series and it shows.
Third: the sound.
The sound is ok. It's very, VERY bland, but it highlights the plot points in a way that does not feel jarring or forced.
Fourth: the characters.
The characters are the strong point of the series.
First of all the main protagonist is what will make or break this series for You. He is egotistical, somewhat cynical and very capable/talented. Think 'House M.D.' without the drugs and targeted at a slightly younger audience. I liked him quite a bit.
All other characters aren't really worth mentioning - except our antagonist. He is presented as a clear and distinctive polar opposite of the main hero. While his actions may seem objectively insane they are indeed well-grounded in his backstory and emotional traits. Like Batman and Joker, they both complement each other.
Go watch it for God's sake! I don't know if You'll fall in love with it but I can safely bet You'll like it quite a bit.